An analysis of the fossil fuel production record since 1860 shows that the exponential growth in production is modulated in the inverse sense by variations in global average temperature. Taking this modulation into account shows that the underlying rate of increase is about 25% less than the widely quoted 4.3% annual rate. This modulation may also produce a partially ameliorating feedback if the often predicted carbon dioxide greenhouse effect actually materializes. 相似文献
The “filter model” has been developed to explain the biologic effects of radiation and chemicals. We have examined nearly 300 sets of dose response data, of which 50 are presented here. Responses (induced by radiation and chemicals) which have been examined include in vitro survival studies on animal and plant tissues, induction of cellular aberrations and time to tumor or death. Similar data from in vivo studies has also been examined. All of the data appear to fit the model R = a lnD + b(lnD)2 + c, where R is the response, a and b are parameters fitted by regression to a particular set of data, and c is the response at zero (or lowest) dose. By writing this model in exponential form, it can be seen that the response R results from multistage filtering (by net amounts a and b) of the initial dose, D. The threshold is obtained from this model as the point, , at which the second derivative becomes zero. This is given by when a and b are oppositelt signed. 相似文献
The purpose of this study is to evaluate the effect of reductions of reactive organic gases (ROG) and NOx emissions on short-term O3 and NO2 concentrations and annual average NO2 concentrations in the California South Coast Air Basin. Short-term air quality predictions were obtained by applying the Systems Applications Airshed Model to summer O3 and autumn NO2 episodes. Effects of emission controls on annual NO2 concentrations were estimated using CDM and a new parcel tracking model NOXTRAK. Results for the summer O3 episode indicate that ROG emission reduction in an effective means for reducing peak O3 concentrations. NOx emission reduction imposed in addition to ROG emission reductions are counterproductive in reducing peak O3 concentrations. The modeling results also suggest that attainment of the 1-h federal O3 standard requires ROG emission reductions on the order of 80% from 1987 levels. Results for the autumn NO2 episode indicate that NOx emission reductions approximating those recommended in a proposed Air Quality Management Plan (about 22%) will result in only small (about 5%) reductions in the peak NO2 concentrations. ROG emission reduction may be more effective than NOx emission reduction in reducing the peak NO2 concentration. For the episode studied, a reduction of 36% in ROG emissions is estimated to result in a reduction in peak NO2 concentrations commensurate with that required to attain the 1-h state NO2 standard. Model calculations also indicate that the federal NO2 standard may not be meet by 1987 at one or two stations, but may blosely approached. 相似文献
Based on a feasibility study, we have recently proposed a multivariate regression model for the impact of air pollution on the mortality of a long-term exposed population. This article proceeds by providing some experimental results, since this model has been fitted to data on a cross sectional basis for 41 census tracts in the Munich metropolitan area. The results obtained so far could be supportive to more detailed epidemiological studies of air pollution which have been conducted in many industrial countries; unfortunately, only relatively few have been conducted in West Germany. 相似文献
Sustainability indicators are well recognized for their potential to assess and monitor sustainable development of agricultural systems. A large number of indicators are proposed in various sustainability assessment frameworks, which raises concerns regarding the validity of approaches, usefulness and trust in such frameworks. Selecting indicators requires transparent and well-defined procedures to ensure the relevance and validity of sustainability assessments. The objective of this study, therefore, was to determine whether experts agree on which criteria are most important in the selection of indicators and indicator sets for robust sustainability assessments. Two groups of experts (Temperate Agriculture Research Network and New Zealand Sustainability Dashboard) were asked to rank the relative importance of eleven criteria for selecting individual indicators and of nine criteria for balancing a collective set of indicators. Both ranking surveys reveal a startling lack of consensus amongst experts about how best to measure agricultural sustainability and call for a radical rethink about how complementary approaches to sustainability assessments are used alongside each other to ensure a plurality of views and maximum collaboration and trust amongst stakeholders. To improve the transparency, relevance and robustness of sustainable assessments, the context of the sustainability assessment, including prioritizations of selection criteria for indicator selection, must be accounted for. A collaborative design process will enhance the acceptance of diverse values and prioritizations embedded in sustainability assessments. The process by which indicators and sustainability frameworks are established may be a much more important determinant of their success than the final shape of the assessment tools. Such an emphasis on process would make assessments more transparent, transformative and enduring. 相似文献
The diminishing resources and continuously increasing cost of petroleum in association with their alarming pollution levels from diesel engines has led to an interest in finding alternative fuels to diesel. Emission control and engine efficiency are two of the most important parameters in current engine design. The impending introduction of emission standards such as Euro IV and Euro V has forced research towards developing new technologies for combating engine emissions. This paper examines the effects of compression ratio, swirl augmentation techniques and ethanol addition on the combustion of compressed natural gas (CNG) blended with Honge oil methyl esters (HOME) in a dual fuel engine. The present results show that the combustion of HOME and 15% ethanol blend with CNG induction in a dual-fuel engine operated in optimized parameters at an injection timing of 27° Before Top Dead Centre and a compression ratio of 17.5 resulted in acceptable combustion emissions and improved brake thermal efficiencies. The implementation of swirl augmentation techniques increased brake thermal efficiencies (BTEs) and considerably reduced combustion emissions such as smoke, HC, CO and NOx. The addition of ethanol also increased BTEs. However, at more than 15% of ethanol in HOME, NOx emissions increased dramatically. 相似文献
Carbonized wood is a biofuel from cellulose pyrolysis with frequent smoke and life-threatening carcinogenic emissions. Carbon monoxide (CO), particulate matter (PM2.5), metalloids and trace elements from charcoals from six commonly used tropical timbers for carbonization in Donkorkrom (Ghana) were assessed. During combustion, Anogeissus leiocarpa charcoal emitted the least CO (4.28 ± 1.08 ppm) and PM2.5 (3.83 ± 1.57 μg/m3), while particulate matter was greatest for Erythrophleum ivorense (28.05 ± 3.08 ppm) and Azadirachta indica (27.67 ± 4.17 μg/m3) charcoals. Erythrophleum ivorense charcoal produced much lead (16.90 ± 0.33 ppm), arsenic (1.97 ± 0.10 ppm) and mercury (0.58 ± 0.003 ppm) but the least chromium (0.11 ± 0.01 ppm) and zinc (2.85 ± 0.05 ppm). Nickel was greatest for A. indica charcoal (0.71 ± 0.01 ppm) and least for Vitellaria paradoxa (0.07 ± 0.004 ppm). Trace elements ranged from 342.01 ± 2.54 ppm (A. indica) to 978.47 ± 1.80 ppm (V. paradoxa) for potassium and 1.74 ± 0.02% (V. paradoxa) to 2.24 ± 0.10% (A. indica) for sulphur. Besides A. leiocarpa charcoal, which ranked safest during combustion, the high PM2.5 and CO emissions make the other biofuels hazardous indoors. Kitchens need air filters to absorb these emissions together with the use of improved cook stoves. These carcinogenic metalloids would necessitate that their ashes be properly discarded without human contact. Yet, the charcoals would be much suitable as soil amendment bio-char for plant growth quality improvement.
Illegal wildlife crime is a global phenomenon, accelerating the ongoing biodiversity crisis. In the Old World, and particularly in Africa, illegal use of poisons to eliminate carnivores is the main driver of the continental vulture crisis. Knowledge about the underlying source and drivers of this threat is lacking for most areas, including Kenya, a global vulture and biodiversity hotspot. An extensive questionnaire survey of over 1300 respondents was run, using a specialized questioning technique and quantitative analytical approaches. Results show that, while pastoralists have a positive attitude towards vultures, over 20% of them use poisons to eliminate predators. Poisoning was largely driven by livestock losses to predators, and by negative attitude towards predators. Poisoning was less prevalent among respondents aware of the Kenya Wildlife Act. Overall, we suggest that a combination of top-down, e.g. legislation, and bottom-up (such as corrals or compensation) along with awareness campaigns may help reduce poisoning on the ground.Supplementary InformationThe online version contains supplementary material available at 10.1007/s13280-021-01695-8. 相似文献